1. Field of the Invention
This invention relates to a cam follower apparatus for use in a rocker arm or valve lifter of an engine valve actuating mechanism.
2. Description of the Related Art
In a cam follower apparatus having a structure in which a roller is supported rotatably relative to a supporting shaft, theoretically it comes that the roller is in a rolling contact with a cam. However, sometimes the roller becomes incapable of performing a pure rolling motion relative to the cam due to a change in rotation speed of the roller resulting from the shape of the cam or a sudden change of load applied on the bearing. Therefore, instead of pure rolling motion, a rolling contact is accompanied by sliding motion. In such a case, when the roller comes into sliding contact with the cam, heat is produced, so that wearing, damage and baking are produced easily. As a result, the cam follower apparatus wears prematurely. Therefore, improving lubrication between the roller and cam is very important in the engine valve actuating mechanism using this cam follower apparatus so that durability is improved and maintenance is reduced.
In diesel engines or the like, engine oil is deteriorated by blowby gas so that a combustion product such as soot is likely to be produced. When the above cam follower apparatus is used in a diesel engine or the like having such feature, the lubrication performance of the roller is considerably lowered by the combustion product such as soot, so that the aforementioned wearing, damage or baking occur prematurely.